Borderline personality disorder (BPD) is a serious mental illness that adversely affects individuals, families, and society. Many individuals with BPD engage in high rates of self-harm behavior (e.g., cutting), meet diagnostic criteria for multiple Axis I disorders, attempt or commit suicide at high rates, utilize inpatient and outpatient treatment services at disproportionate rates, and have high rates of substance use disorders. When attempting to explain the maladaptive behaviors associated with BPD, current theoretical models emphasize 1) difficulty regulating emotional states and 2) impulsivity. The research literature suggests that these constructs are core features of BPD. Over the past 30 years, laboratory paradigms have been developed to assess emotion and impulsivity. Psychophysiological measurement paradigms, particularly the measurement of the startle reflex, have greatly informed the study of emotion. In addition, behaviorally based laboratory measures have been developed to assess various aspects of impulsive behaviors. Laboratory methods have the advantage of more directly tapping the basic processes underlying these constructs and may add important information to verbal responses collected using self-report measures. Despite the experimental advances and the importance ascribed to emotion dysregulation and impulsivity in theoretical models of BPD, few laboratory studies have been conducted to explicate the role that these constructs play in BPD. We believe that by using psychophysiological methods to more thoroughly measure emotion, and laboratory measures to assess impulsive behavior, theoretical models of BPD can be further developed and refined. The current application proposes to measure emotional reactivity, using both imaginal and visual stimuli, and impulsivity, using laboratory tasks designed to measure three conceptualizations of impulsivity: 1) cognitive decision making about future consequences, 2) behavioral inhibition, and 3) risk-taking. Ultimately, gaining a better understanding of emotion dysregulation and impulsivity from laboratory studies may improve the identification and treatment of BPD. [unreadable] [unreadable]